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Spider decorator crabs take camouflage to an extreme - they attach algae, sponges, small corals, and any available debris to specialized hooked hairs on their body, becoming nearly invisible. Long thin legs give them the "spider" appearance. Best appreciated in tanks where you can witness their decorating behavior. Peaceful and reef-safe.
Native range: Indo-Pacific. Most US trade specimens come through marine wholesale suppliers in Indonesia, the Philippines, Hawaii, and the Caribbean. Wild collection remains the primary sourcing method for the majority of marine inverts - few are captive-bred at commercial scale. Quality of acclimation at the wholesale/retail stage is the biggest single predictor of long-term survival in home aquaria.
Tank size: 30 gallons. Parameters: temperature 74-82°F, salinity 1.024-1.026, plus the standard reef tank requirements - stable calcium 420-440 ppm, alkalinity 8-10 dKH, magnesium 1300-1400 ppm, nitrate under 25 ppm, phosphate under 0.05 ppm. The species requires conditions consistent with a healthy reef tank rather than nutrient-stripped sterile water - well-established systems with diverse microfauna and biofilm typically support these inverts better than newly-cycled tanks.
Lighting: depends on species. Photosynthetic inverts (clams, anemone-symbiotic species) require high-PAR reef LED lighting. Filter-feeders (worms, scallops) prefer moderate lighting and benefit from particulate-rich water. Flow: moderate, indirect flow works for most inverts - direct high-velocity flow stresses or damages soft-bodied species.
Acclimation: drip acclimate over 2-4 hours for hardy species, 4-8 hours for sensitive species (Linckia stars, sea hares, demanding nudibranchs). Never expose inverts to air during transfer - capture in a bowl underwater and transfer wet.
Spider Decorator Crab diet: Algae, detritus, occasional small meaty foods. Feeding strategy depends on dietary type. Algae eaters require established tanks with biofilm and microalgae growth - new tanks lack the algal base they need. Carnivore inverts (starfish, some snails) need targeted meaty feedings 2-3x weekly. Filter feeders (clams, worms, scallops) need phytoplankton in the water column. Photosynthetic species need adequate lighting plus supplemental amino acid or coral food dosing.
Safe: Peaceful reef community.
Avoid: Larger predatory crabs, large hermits.
Not captive bred.
Frag "borrowing" (usually harmless); difficult to spot in well-decorated form.
Yes - peaceful and ignore corals (except for occasionally borrowing small frags for decoration).
Occasionally - they will attach small frags to their body. Frags usually survive and detach later. Cement larger valuable frags to rock.
$15-30 each.
Camposcia retusa is the most common decorator crab species. Other species (Maja crispata, Dromia personata) are sold less frequently with similar behavior.
Fast Aquatics vendors ship marine inverts overnight to all 50 US states with carrier-tracked Buyer Protection.
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